This invention relates to rolled material dispensers and, more specifically, to a flexible sheet material dispenser such as usable for dispensing paper towels with a cutter mechanism housed within the feed roller of the dispenser adapted to cut a web of flexible sheet material into individual lengths of the material.
Dispensers for rolled flexible sheet material, such as paper toweling, are well known, a great many of such dispensers including mechanisms for perforating or severing a web of the material to divide the web into individual sheets. The perforating or severing mechanism used in a number of these dispensers has included a rotatably mounted knife and a cooperating rotatably mounted roller having a slot therein for receiving the radially outermost portion of the knife as the knife rotates past the roller. A web of flexible sheet material is passed between the roller and the knife to be perforated or severed when the radially outward knife portion enters the slot in the roller.
Such mechanisms are satisfactory for perforating or severing relatively unstretchable flexible sheet materials, such as uncreped paper toweling. However, with the increased use of relatively stretchable flexible sheet materials, such as embossed or creped paper toweling, the prior art perforating and severing mechanisms have proved unsatisfactory because the web of sheet material tends to stretch about the cutting edge of the knife instead of being effectively perforated or severed thereby.
Although precision rotary shears are known which could be employed to overcome this problem, such shears are much too expensive to be used in flexible sheet material dispensers designed for installation to be used in both commercial and private washrooms.
Various devices for cutting off sheets of creped web material have been proposed. One is exemplified in DeLuca U.S. Pat. No. 4,188,844 issued Feb. 19, 1980, wherein a toothed knife is pivotally mounted internally of the feed roller within the towel dispenser. However, the towel cut produced by these internal pivoted toothed knives produces a wavy shape due to the pivoting action which the toothed knife undergoes. The points and roots of the straight knife teeth do not emerge from the feed roller on a straight line. Where the cutting knife is mounted to be movable radially outwardly from within a roller over which a web of paper is passing, this radially movable cutting knife unduly stretches the paper away from the feed roller without properly cutting the web.
In dispensers for crepe paper toweling where the cutting mechanism is intended to be actuated solely by pulling on the paper web, usually with the web hands of the intending user, it is important that the required pulling force be minimized to prevent the web from tearing prematurely in the intending user's fingers. To minimize the tearing effort, the cut must be as short as possible and hence must be 90.degree. to the length of the web of sheet material and without a wave form at the location of the web cut. In dealing with crepe paper toweling, the cutting mechanism must also be designed such that the cutting mechanism will effectively cut the paper with a minimum of paper movement and not significantly stretch the creped paper.